Dielectric measurements of epoxy resin/ BaTiO3 fiber composites

H. A. ÁVILA; L. A. RAMAJO; M. S. GÓES; M. M. REBOREDO; M. S. CASTRO; R. PARRA

Aveiro

Congreso; 21st IEEE International Symposium on Applications of Ferroelectrics (ISAF-2012); 2012

IEEE y University of Aveiro

Integrating the advantages of polymer and ceramic materials, composites can offer enhanced performances compared to those of the individual constituents. Varieties of ceramic/polymer composites have been developed. Among them, composites with dielectric and ferroelectric properties have attracted much attention recently. In this work, composite materials composed of epoxy resin and BaTiO3 (BT) nanofibers obtained by electrospinning, were prepared. Nanofibers were synthesized from a sol based on barium acetate, titanium isopropoxide and poly(vinyl pyrrolidone). Fibers were calcined at different temperatures and characterized by X-Ray diffraction, field-emission scanning electron microscopy and Raman spectroscopy. Mats of BT fibers heat-treated at 800°C were embedded in epoxy resin inside suitable moulds. The resulting epoxy resin/BT composites were cured and subsequently analyzed by SEM and impedance spectroscopy analyses. The dielectric constant and hysteresis loops of epoxy resin/BT-fibers were measured for two types of samples with the electrodes parallel and perpendicular to the BaTiO3 fiber layers. Samples with electrodes perpendicular to the array of fiber mats showed higher real permittivity values and ferroelectric behavior, whereas samples with parallel electrodes showed permittivities similar to that of epoxy resin. Additionally, the dielectric results of epoxy/BT fibers composites confirmed predictions of the Hashin-Shtrikman?s series and parallel mixing model.